Homopolar generator



Jan. 30, 1934. F. K. ROUGE ET AL 1,944,952

4 HOMOPOLAR GENERATOR Filed Jan. 29. 1952 s sheets-snee; 2

FFA NA K ROUGE MABBT .Bl SFEZE ERASMUS D SMITH MAM/m Jan 30, 1934- F. K.ROUGE Er AL 1,944,952

HOMOPOLAR GENERATOR FledJan. 29. 1932 3 Sheets-Sheet 3 atto@ M115Patented Jan. 30, 1934 PATENT OFFICE HOMOPOLAR GENERATOR Frank K. Rouge,Mamma B. Steele, and Erasmus' D. Smith, Cleveland, Ohio, assignors toSteel and Tubes, Inc., Cleveland, Ohio, a corpora.-

tion of Ohio Application January 29, 1932. Serial No. 589,680

16 Claims.

This invention relates to dynamo electric machines of the homopolar typeand is particularly concerned with the provision of a new and improvedhomopolar generator having increased capacity with given physical'dimensions, having positive and eilicient means for conducting currentfrom movable to stationary parts without arcing and its attendantdisadvantages, and having new and novel means for collecting and leadingoff the current in such a manner that the current has the eifect ofcreating an additional magnetic flux supplementing. the main magneticiiux.

Referring now to the accompanying drawings in which preferred and modiedforms of the invention are shown:

Figure 1 is a side elevation partly in section of an improved homopolargenerator constructed in accordance with the principles of theinvention.

Figure 2 is a sectional view taken substantially along the lines 2--2 ofFigure l.

Figure 3 is a plan View of a pair of brushes employed in carrying outthe present invention.

Figures 4 and 4a are end and side elevational views respectively of animproved collector bus for use with present invention.l

Figure 5 is a side elevation, partly in section, of a modified form ofgenerator constructed in accordance with the principles of theinvention.

Figure 6 is a view of a collector ring used in connection with thisinvention.

In all of the above described views like characters of reference areemployed to designate like parts throughout.

The device involves in its general organization two end or core pieces land 2. These core pieces are substantially identical having the likeportions thereof facing each other and provided with central openings 3in which bearings 4 are mounted in the hub portions of the core pieces.These bearings are adapted to receive an armature shaft 5 thereacross.The bearings 4 are provided with lubricating devices 6 in the form ofgrease cups which occupy an exposed position on the outside of themachine. The core pieces l and 2 are substantially of annular form butare provided with integrally formed feet l which provide a base for theentire machine.

The core pieces 1 and 2 are spaced from each other by means of a casting8 in the form of an annular pole piece 9 located centrally of themachine and surrounding the shaft 5, from which pole piece thereprojects a plurality of axially extending, relatively heavy cross bars10. These bars are spaced around the periphery of the machine and theinner faces of the core pieces 1 and 2 and are secured to these bars 10at their ends by means of securing bolts 11. The core pieces 1 and 2 arein effect pole pieces which pole pieces in conjunction with the polepiece 9 and the an- 00 nular extending arms or cross bars 10 form aportion of the path of dow of magnetic flux. The remainder of the pathis completed through an armature 12 in the form of an annular bmbf ofmagnetic material of high permeability mounted on the shaft 5 betweenthe core pieces 1 and 2. This armature is provided with a peripheralsurface 13 slightly spaced from the inner annular surface of the polepiece 9 by an air gap which gap is of substantially constant Widtharound the periphery of the armature. Radial air gaps 14 are likewiseprovided between the vertical sides of the armature and the core pieces1 and 2. In order to reduce the size of these air gaps 14 to a minimum apair of steel plates 15 of ring-like formation are secured to theopposed faces of the pole pieces 1 and 2. These steel plates are securedin position by means of counter sunk screws 16. The plates 15 areaccurately machined as are the opposite radial faces of the armature,and care should be taken to insure that the radial air gaps 14 shall beof equal thickness Within very close limits to prevent slight endwise oraxial movement of some of the parts due to magnetic forces, withresultant seizure of the parts or breakage of the bearings. In order toreduce the air gap 17 between the peripheral surface 13 of the armatureand the inner surfaces of the pole piece 9 these surfaces are alsoaccurately machined. The steel plates 15 perform a dual function in thattheir outer peripheries project beyond the hubs of the core pieces 1 and2 and serve to retain a pair of magnetizing coils 18 in position on thecore pieces.

The magnetizing coils 18 which serve to magnetize both the eld magnetand the armature 12 are set in cut-away portions 19 formed in the hubsof the pole pieces 1 and 2. These coils are held in position by thesteel retaining plates 15 as above described. The coils are insulatedfrom the field magnet by means of suitable insulation 20. 'I'hisinsulation is of waterproof nature and extends completely around thecoils to protect the same from the deleterious effect of cooling fluidcirculated within the machine. The coils are disposed on opposite sidesof the armature adjacent its outer periphery.

The armature 12 is keyed to the shaft 5 as at 21. The periphery of thearmature is threaded on opposite sides of the armature as at 22 andthese threaded portions of the armature receive thereon metallic ringmembers 23 and 24, which have their inner ends threaded as at 25, bymeans of which holder studs 36 extend into the ring they are threadedlyreceived on the threaded portion of the amature.

'I'he ring members 23 and 24 telescopically receive collector rings 26and 27 respectively thereon which collector rings may be insulated fromthe ring members 23 and 24 by means of suitable insulation 28. Thesurface of these rings may be suitably grooved either circumferentiallyor spirally as shown in Figure 6. 'I'his provision will break up thefilm of cooling liquid which collects on the ring and causesunsatisfactory contact be tween the brushes and the ring. A plurality ofaxially extending amature conductors 29 may be insulated by suitableinsulation 30 from the walls of holes passing through the armature nearthe periphery surface of the latter. The ends of the armature conductorsproject from the ends of the armature at opposite ends thereof and aresecured to the collector rings 26 and 27 in any suitable manner as forexample by welding or the like. The collector rings 26 and 27 areslightly spaced from the sides of the armature and provide annulartroughs or grooves 31 which troughs or grooves are spanned by thearmature conductors. In view of the fact that cooling fluid circulateswithin the space between the pole pieces l and 2, in a manner and for apurpose to be described more fully hereinafter, these annular troughs 31are filled with any suitable filler material to prevent churning of thecooling fluid.

Insulated from but secured to the inner faces of the pole pieces 1 and 2by means of securing bolts 32 and 33 are a pair of collector busses 34and 35. Each of these busses consists of a split ring having a narrowgap between the ends and an extension projecting radially outwardly fromone end. They are mounted coaxially with and radially outside of thefield coils.

A plurality of brush holder studs or pins 36 extends into the ring-likeportion of the collector busses 34 and 35. These brush holders are inthe form of inwardly extending pins having mounted thereon split collars37 which are secured in position on the pin 36 by means of bolts 38. Thecollar 37 carries brush sockets 39 on opposite sides in which thebrushes 40 are mounted. The surfaces of the brushes 40 have suitablegrooves 40a formed on the contacting surface thereof. These grooves areeffective in breaking up any film of cooling liquid which might formbetween the es and the collector rings in a liquid cooled device. Whengrooved collector'rings are used. brushes 40 may be plain surfaced, andwhen grooved brushes are used the collector rings may be plain or smoothsurfaced. In other words, only one of these two members need be grooved.'I'he brushes bear on the collector rings 26 and 27 held by brushpressure fingers (not shown) to conduct current generated in thearmature conductors 29 to the collector busses 34 and 35.

Referring now to Figures 4 and 4a one of the improved collector busses35 is shown as being in the form of a split ring terminating in aradially extending lead off portion 42. This ring 4l is comprised of a.plurality of arcuate copper strips secured together to form a built upstructure. These strips are designated at 41, 43, 44, and 46, and are ofprogressive decreased circumferential lengths so that the ring portionof the bus-bar becomes progressively thicker around its periphery towardthe lead oi portion 42. The brush shaped portion of the collector busand are equi-distantly spaced around the same. As shown in the drawingsthree brush holder studs are connected to each segment of the ringportion of the collector bus and inasmuch as each of the segments of thering portion is of increased cross sectional area the current dischargedinto the collector bus by means of the studs 36 is conducted to theterminal connection 42 at substantially uniform densities. The terminalconnections 42 which project radially outward from the pole pieces 1 and2 consist in a pair of copper strips whose combined cross sectional areais equal to the cross sectional area of the strips making up the splitring adjacent the end of the latter. To accommodate the terminalconnections 42, two of the strips for example the strips 44 and 46project beyond the ends of the strips 43 and 45. One strip forming ahalf of the terminal connection 42 is sandwiched, so to speak, betweenthe ends of the strips 44 and 46 the other strip forming a half of theterminal connection 42 is bolted to the strip 46 on the outside thereof.By the use of a built up bus-bar such as has been disclosed, aconducting path is provided which is ample to accommodate a high currentflow and which results in a saving of metal.

The improved generator embodies in its general organization a novelmeans by which the machine may be cooled. Towards this end means isprovided for introducing a cooling fluid into the interior of themachine between the pole pieces 1 and 2. The pole pieces l and 2 projecta slight distance beyond the outer surfaces of the cross bars 10 and aflexible metal cover plate for the machine fits closely around theoutside of the members l0, being centered by the projecting portions ofthe pole pieces 1 and 2. This flexible cover is designated at 47.

At diametrically opposed points on the cover there is provided an inlet48 and an outlet 49 for the passage of cooling fluid. The height of theoutlet 49 determines the level of cooling fluid in the machine. Whilethis cooling fluid may be any suitable liquid it is preferable thatwater be employed on account of the accessibility of the same for useand on account of its abundancy and comparatively small cost.

In actual operation as the armature 12 is rotated the conductors 29 cutthe lines of magnetic force provided by the field magnet in itssubstantially uniform magnetic field in the same direction irrespectiveof their position in space. In order to maintain a uniform magneticfield the air gaps 14 and l5 are reduced to a minimum in the mannerpreviously described. In addition to this the pole pieces 1, 2 and 9taper radially outwardly and are accurately designed so that a sectionalarea around the pole pieces otl'ers a cross sectional area that isuniform. VIn other words the path of the magnetic flux through themetallic portion of the machine is a constant cross sectional area. Asthe conductors cut the magnetic lines of force a constant and uniformcurrent is induced into these conductors and is discharged into thecollector rings 26 and 27. This current is picked up by the brushes 40and is conducted through the brush holder studs 36 to the busses 34 and35.

Inasmuch as the busses 34 and 35 surround the hubs of the pole pieces 1and 2 and are concentric with the eld coils 18 these busses have theeffect of creating a series field supplementing the field maintained bythe usual field coils 18. Thus when a relatively large current isflowing through the busses, an additional flux supple- A inenting theflux created by the field coils 18 is caused to flow around the fluxpath;

It will be understood by those skilled in the art from the precedingdescription that a homopolar generator has been provided which is welladapted for the purposes intended. The provision of a grooved contactsurface between each collector ring and its brushes insures goodelectrical contact between these members even in the presence of coolingliquid, which might have a tendency otherwise to form a film between theopposed members and thus makes possible the operation of the device inthe presence of a cooling liquid at increased current densities withoutarcing and its attendant advantages. Moreover, the novel and efiicientcooling means increases the capacity of the machine as contrasted withprevious cooling methods. Furthermore, the collector busses, due totheir form and arrangement with respect to other parts of the device,create a magnetic flux which is additional to and which supplements thatof the field coils. This additional ux counterbalances the usualdemagnetizing effect and its consequent decreases of terminal voltagewith increases of load.

Referring now to Figure 5, a modified form of generator is disclosed. Inthis form in the magnetic circuit all radial air gaps have beeneliminated. The machine involves in its general organization a corepiece 50 in the form of a casting providing a central pole piece 51 andouter pole pieces 52 and 53. The outer pole pieces are connected to thecentral pole piece by means of relatively heavy bars 54. These bars arespaced uniformly around the periphery of the machine. The pole piece 51and the pole pieces 52 and 53 form a portion of the path of magneticflux and the remainder of the path is completed through an armature 55.This armature is in the form of a cylindrical mass of magnetizablematerial mounted on a central shaft 56 journalled in anti-frictionbearings 57 carried by end plates 58 which form a part of the casing ofthe machine.

The end plates 58 are in the form of annular disc-like members havingtheir peripheries connected to the pole pieces 52 and 53 respectively.These end plates are provided with central openings 59 through which theshaft 56 extends. The anti-friction bearings 57 are4 carried within alubricant chamber 60 to the interior of which chamber a lubricant isconducted through a bore 61 having a grease cup 62 or similar connectionassociated therewith.

The armature which is keyed to the shaft 56 is of substantiallycylindrical formation and is provided with a pair of annular troughs 63.The armature 55 is provided with a central projecting portion 64 ofsubstantially the same width as the width of the pole piece 51 at itsinner surface. and 66 are also provided on the amature 55 and theselatter projecting portions are of substantially the same width as thewidth of the pole pieces 52 and 53 respectively. A relatively narrow airgap 67 of uniform thickness exists between the projecting portion 64 ofthe armature and the pole piece 51 and relatively narrow air gaps 68 and69 exist between the projecting portion and 66 and the pole pieces 52and 53 respectively.

A plurality of armature conductors 70 extend longitudinally through theprojecting portion 64 of the armature 55 just inwardly of the peripherythereof. The opposite ends, so to speak, of the A pair of annularprojecting portions 65 projecting portions 64 are threaded as at 7l andtelescopically received on these threaded portions 71 of the armatureare a pair of ring members 72. These ring members each serve to carry acollector ring 73 into which rings the ends of the armature conductors70 extend. The arrangement of armature conductors and collector rings inthis modification of the invention is'similar to the arrangement ofarmature conductors and collector rings shown in the form of theinvention disclosed in Figures 1 and 2, and the type of grooved brushesand collector rings may be used as advantageously.

The field coils are designated at 74. These field coils are mounted uponspaced brackets 75 carried by the end pole pieces 52 and 53. The eldcoils 74 are annular in form and extend around the armature structure. Asuitable insulation material 76 of liouid proof character covers thesecoils to protect the same from the cooling fluid circulated through themachine.

A pair of collector busses 77 substantially identical in construction tothe busses 34 and 35 in the form of the invention shown in Figures 1 and2 are secured to the pole piece 51 on opposite sides thereof by means ofsecuring bolts 78. These busses are of a built-up structure and carrybrush holder studs '79 similar to the brush holder studs 36, These brushholders carry brushes 80 which bear upon the collector rings 73 tocollect and transmit current generated by the armature conductors 70.

.The generator disclosed in this form of the invention as well as in theother form disclosed is designed to accommodate the novel water coolingfeature embodied in this invention. Toward this end an inlet 81 isprovided in one of the end plates 58 adjacent the bottom of the machineand an outlet 82 is provided in the other end plate adjacent the top ofthe machine. A suitable exible cover 83 closes the central portion ofthe machine and this cover rests upon the pole piece 51 and has itsopposite edges sealed against the pole pieces 52 and 53. Any suitableclamping means (not shown) may be employed for maintaining this cover inposition. A cooling medium is circulated through the machine through theinlet 81 around the air gaps 68, 67 and 69 and is carried away from themachine through the outlet 82.

It is to be particularly noted that in this form of the invention thereare no radial air gaps and consequently the danger of end thrust of thearmature shaft is substantially eliminated.

The invention is not to be limited to the exact arrangement of partsshown in the accompanying drawings or described in this specification asvarious changes in the details of construction may be resorted towithout departing from the spirit of the invention. Only insofar as theinvention has been particularly pointed out in the accompanying claimsis the same to be limited.

I claim:

1. In a dynamo-electric machine an annular armature having a pluralityof armature conductors mounted thereon, a pair of collector rings spacedfrom said armature on opposite sides of the same and adapted to rotatetherewith, the opposite ends of said armature conductors projecting fromthe armature and being secured to said collector rings, said collectorrings and armature dening spaces for the reception of filler materialand iiller material disposed in the said spaces between said armatureand collector rings.

2. In a dynamo-electric machine a rotatable armature having armatureconductors mounted ing field coils covered by a liquid proof material, apair of collector rings connected to the ends of said armatureconductors, brushes bearing on said collector rings. collector busseselectrically connected to said brushes and a cooling liquid disposedwithin said field structure and in contact with said armature, collectorrings and brushes.

3. In a dynamo-electric machine, the comb ination with an annular polepiece providing a portion of the path of magnetic flux, said pole piecebeing surrounded by field coils, of a collector bus surrounding saidpole pieces and supplementing the field maintained by the field coils.

4. In a dynamo-electric machine, the combination with a pole piecehaving field coils, of a collector bus supplementing the fieldmaintained by said field coils.

5. In a dynamo-electric machine, a central pole piece, a pair of endpole pieces said pole pieces having projections thereon defining achamber, a rotatable armature disposed within said chamber integrallyformed of a mass of magnetizable material and having annular projectingportions extending toward said pole pieces respectively and formingrelatively narrow axial air gaps therewith.

6. In a, dynamo-electric machine, a plurality of ring shaped pole pieceshaving projections thereon defining a chamber, a substantiallycylindrical armature disposed within and substantially filling saidchamber presenting axial air gaps with respect to said pole pieces, saidarmature, throughout its entire length, projecting no further than theouter limits of said pole pieces.

7. In dyanmo-electric machine having a rotatable armature and armatureconductors mounted thereon, a field structure for said armature, fieldcoils, collector busses supplementing the flux maintained by said fieldcoils, a pair of collector rings connected to said armature conductors,brushes bearing on said collector rings, said brushes having groovesformed in their bearing surfaces, and a liquid cooling me dium disposedwithin said field structure in cooling contact with said armature,.collector rings and brushes.

8. The combination with a collector ring for liquid cooleddynamo-electric machines having field coils, of brushes bearing on saidcollector rings, said brushes having a plurality of grooves formed intheir bearing surfaces and collector busses of ring-like configurationspositioned to supplement the field of the field coils.

9. In a dynamo-electric machine, an annular armature having a pluralityof axial armature conductors mounted thereon, and a pair ofcollectorrings mounted on said armature, grooves formed on the contactingsurfaces of said collector rings. the opposite ends of said armatureconductors extending into said collector rings.

10. In a dynamo electric machine, an annular i armature having aplurality of armature conductors mounted thereon, a pair of collectorrings molmted on said armature and insulated there- 1,944,952 rthereon,a field structure for said armature havfrom, grooves formed on thecontacting surfaces of said collector rings, the opposite ends of eacharmature conductor extendingv into said collector rings.

11. In a dynamo-electric machine, a central pole piece, a pair of endpole pieces, said pole pieces denning a chamber, a rotatable armaturesubstantially filling said chamber and rotatable therein, said polepieces substantially confining said armature on all sides thereof insuch a manner as to form relatively narrow air gaps therebetween.

12. In a dynamo electric machine, an annular armature having a pluralityof axial armature conductors mounted thereon, a pair of collector ringsmounted on said armature and adapted to receive the ends of saidarmature conductors, brushes bearing on said collector rings, acollector bus adapted to support said brushes comprising a split ringmember positioned to supplexnent the flux of the field coils.

13. In a dynamo electric machine, an annular armature having a pluralityof armature conductors mounted thereon, a pair of collector ringsmounted 0n said armature and adapted to receive the ends of saidarmature conductors, brushes bearing on said collector rings, polepieces being surrounded by field coils, a collector bus surrounding saidpole pieces and adapted to support said brushes, said collector busadapted to supplement the field maintained by said field coils.

14. In a dynamo electric machine, a shaft, a central pole piece, a pairof end pole pieces, said shaft and pole pieces defining an annularchamber, a rotatable armature consisting of a mass of magnetizablematter and substantially filling said chamber, said armature beingspaced apart from the said pole pieces by relatively narrow air gaps,the air gaps between the said armature and the end pole pieces being ofequal thickness within very close limits.

l5. In a dynamo electric machine, a rotatable armature having aplurality of armature conductors mounted thereon, a pair of collectorrings mounted on said armature and connected to said armatureconductors; brushes bearing on said collector rings, one of the opposedsurfaces of each set of collector rings and brushes being provided witha plurality of grooves, and collector busses connected to said brushes.

16. In a dynamo electric machine, a pole piece having a field coils, arotatable armature having conductors mounted thereon, collector ringsconnected to said armature conductors, brushes bearing on said collectorrings, one of the opposed surfaces of each set of collector rings andbrushes being provided with grooves, split ringlike collector bussesconnected to the brushes and positioned to supplement the fluxmaintained by the field coils, and housing means for maintaining aliquid cooling medium in contact with the armature, collector rings andbusses.

FRANK K. ROUGE. MABBOTT B. STEELE. ERASMUS D. SMITH.

